1. Field of the Invention
The present invention relates to an electrical connector assembly, and particularly to an assembly having a board hold down for detachably holding a circuit board to another circuit board thereof.
2. Description of Related Art
Card edge connectors, such as PCI (Peripheral Component Interconnect) and PCI Express connectors, are widely used to connect daughter cards and mother boards. Typically, each of the card edge connectors generally comprises an elongate housing defining an elongate slot for receiving a mating edge of the daughter card, a plurality of terminals disposed along one or two sides of the slot for engaging conductive pads disposed on the mating edge of the daughter card, and a pair of latch members attached to opposite ends of the housing. For example, U.S. Pat. No. 5,484,302 (the '302 patent) shows such a card edge connector.
The card edge connector of the '302 patent is arranged to be mounted on a mother board and to hold a daughter card in an orientation which is parallel to the mother board. The card edge connector has discrete metal latches held in guide frames which extend outwardly from opposite ends of a housing. A plurality of terminals are received in the housing and have solder tails electrically connected to the mother board by surface mount technology. The latches have integral solder tabs which are also attached to the mother board by surface mounting technology to increase the retention of the card edge connector to the mother board and to reduce stress imposed on the solder connections of the terminals. The solder tails of the terminals and the solder tabs of the latches must be coplanar so that good solder joints can be produced, but it is difficult to ensure a close coplanarity tolerance on these parts. Also, the latches should extend precisely perpendicular to the housing for effectively latching the daughter card and for proper alignment with solder pads on the mother board. There is a need for the card edge connector having improved means for accurately positioning the latches. Further, the guide frames increase a longitudinal dimension of the housing, so large space of the mother board is occupied by the card edge connector. This problem is especially critical in some applications where several card edge connectors are arranged on the mother board side by side.
Hence, an electrical connector assembly having an improved board hold down to solve the above problems is desired.